Conventionally, for example, the hose has been mounted in a connection tube, and has been tightened from an outer circumference thereof by a fastener band so as to be retained and to prevent a water leak. Also, as shown in Patent Document 1, an inner circumferential face of an annular concave portion provided in an inner circumferential face of a receiving opening of a connector main body includes an inclined inner circumferential face whose diameter is reduced toward an opening end side. In the annular concave portion, there is disposed a short cylinder portion of a collet including a flange in one end of the short cylinder portion in a loosely fitted state. In an inner side of the collet, there is disposed a small-diameter short cylinder portion which is provided to extend integrally in the opening end side from a back-portion inner circumferential face of the connector main body concentrically with a shaft center of the connector main body. In an annular groove provided in an outer circumferential face of the short cylinder portion, there is mounted a seal ring.